utils: add filterUnique helper

- use it in groupby transform and findArrayAttributes

Author: etpinard

src/lib/coerce.js

@@ -13,6 +13,7 @@ var isNumeric = require('fast-isnumeric');
 var tinycolor = require('tinycolor2');
 var nestedProperty = require('./nested_property');
 var isPlainObject = require('./is_plain_object');
+var filterUnique = require('./filter_unique');
 
 var getColorscale = require('../components/colorscale/get_scale');
 var colorscaleNames = Object.keys(require('../components/colorscale/scales'));
@@ -466,9 +467,7 @@ exports.findArrayAttributes = function(trace) {
     if(trace._fullInput) {
         exports.crawl(trace._fullInput._module.attributes, callback);
 
-        arrayAttributes = arrayAttributes.filter(function(g, i, self) {
-            return self.indexOf(g) === i;
-        });
+        arrayAttributes = filterUnique(arrayAttributes);
     }
 
     return arrayAttributes;

src/lib/filter_unique.js

@@ -0,0 +1,49 @@
+/**
+* Copyright 2012-2016, Plotly, Inc.
+* All rights reserved.
+*
+* This source code is licensed under the MIT license found in the
+* LICENSE file in the root directory of this source tree.
+*/
+
+
+'use strict';
+
+
+/**
+ * Return news array containing only the unique items
+ * found in input array.
+ *
+ * IMPORTANT: Note that items are considered unique
+ * if `String({})` is unique. For example;
+ *
+ *  Lib.filterUnique([ { a: 1 }, { b: 2 } ])
+ *
+ *  returns [{ a: 1 }]
+ *
+ * and
+ *
+ *  Lib.filterUnique([ '1', 1 ])
+ *
+ *  returns ['1']
+ *
+ *
+ * @param {array} array base array
+ * @return {array} new filtered array
+ */
+module.exports = function filterUnique(array) {
+    var seen = {},
+        out = [],
+        j = 0;
+
+    for(var i = 0; i < array.length; i++) {
+        var item = array[i];
+
+        if(seen[item] !== 1) {
+            seen[item] = 1;
+            out[j++] = item;
+        }
+    }
+
+    return out;
+};

src/lib/index.js

@@ -75,6 +75,8 @@ lib.error = loggersModule.error;
 
 lib.notifier = require('./notifier');
 
+lib.filterUnique = require('./filter_unique');
+
 /**
  * swap x and y of the same attribute in container cont
  * specify attr with a ? in place of x/y

src/transforms/groupby.js

@@ -121,12 +121,9 @@ function transformOne(trace, state) {
         return trace;
     }
 
-    var groupNames = groups.filter(function(g, i, self) {
-        return self.indexOf(g) === i;
-    });
-
-    var newData = new Array(groupNames.length);
-    var len = groups.length;
+    var groupNames = Lib.filterUnique(groups),
+        newData = new Array(groupNames.length),
+        len = groups.length;
 
     var arrayAttrs = Lib.findArrayAttributes(trace);
 

test/jasmine/tests/lib_test.js

@@ -1367,6 +1367,37 @@ describe('Test lib.js:', function() {
         });
     });
 
+    describe('filterUnique', function() {
+
+        it('should return array containing unique values', function() {
+            expect(
+                Lib.filterUnique(['a', 'a', 'b', 'b'])
+            )
+            .toEqual(['a', 'b']);
+
+            expect(
+                Lib.filterUnique(['1', ['1'], 1])
+            )
+            .toEqual(['1']);
+
+            expect(
+                Lib.filterUnique([1, '1', [1]])
+            )
+            .toEqual([1]);
+
+            expect(
+                Lib.filterUnique([ { a: 1 }, { b: 2 }])
+            )
+            .toEqual([{ a: 1 }]);
+
+            expect(
+                Lib.filterUnique([null, undefined, null, null, undefined])
+            )
+            .toEqual([null, undefined]);
+        });
+
+    });
+
     describe('numSeparate', function() {
 
         it('should work on numbers and strings', function() {